1. Field of the Invention
The present invention relates generally to electrical systems and devices with cooling means, more particularly to electrical systems and devices using air for cooling, and most specifically to electrical systems and devices using a fan or blower for cooling.
2. General Background
The current widespread use of computers in the home is considered to have originated with the advent of the IBM (International Business Machines) PC (Personal Computer) in the early 1980s. Subsequent to this introduction diverse companies manufactured and sold what are commonly known as IBM Compatible PCs which are characterized by use of a DOS (Disk Operating System), particularly MS (MicroSoft) DOS and Windows operating systems developed and licensed by Microsoft Corporation. The growth of this industry is considered to have been fueled by the development of faster and more powerful microprocessors such as those developed in the early 1990s by Intel Corporation and others including AMD (Advanced Micro Devices).
The more recent history of this continuing development also is allied with the more recent popularity of the Internet which was first developed by the U.S. Department of Defence and aided by the advent of internet access providers such as AOL (America On ine and internet search engines such as Netscape. This and other capabilities are not of direct concern to the present invention but are merely illustrative of the increased popularity of PCs generally which development has been characterized by the use of faster and more powerful microprocessors which support expanded capabilities for the PC which term is used hereinafter to denote a computer which uses a microprocessor as a CPU (Central Processing Unit) and which are further characterized by the use of a DOS which is inclusive of the Windows operating systems which currently dominate the PC market.
Microprocessors, which are invariably utilized as CPUs in PCs, are electronic devices as are the various solid state transistor based printed circuit boards or `chips` or `cards` typically found in a PC. All of these electronic and the other components of a PC except for the case or housing, known herein as a PC enclosure, including the HDD (Hard Disk Drive), `floppy` disk drives, laser or CD (Compact Disk) drives, generate heat, particularly the A.C. (alternating current) to D.C. (direct current) electrical transformer which, in a PC, is commonly known as the power supply. The amount of heat generated or dissipated by all of these electric components is considerable. One relatively recent PC is noted as using and therefor dissipating 325 W (Watts) of power of which the CPU uses 30 W (U.S. Pat. No. 5,793,608, Abstract).
The operating temperature of the CPU of a PC is considered critical to the speed at which the entire PC operates. Hence while the removal of heat from the case enclosing the PC generally is beneficial and necessary to normal functioning of a PC it is the operating temperature of the CPU which is generally determinative of the speed at which the PC operates. As the microprocessors utilized as the CPU in a PC have become faster and more powerful the operating temperature of the same has become more important. It is stressed that the CPU, along with all the other components of a PC, are enclosed in a case and therefor the ambient temperature inside that case has been of primary concern. It is also stressed that the transformer comprising the power supply of a PC is invariably the greatest source of beat generation in a PC.
It is also noted that virtually all PCs are equipped with at least one fan or blower for cooling the inside of the enclosure provided by the casing of a PC. If only one fan or blower is utilized it is generally an exhaust fan and virtually all PCs have an exhaust fan which is hence considered a given or assumed characteristic of a PC. Additional fans or blowers have also been utilized in PCs including additional devices, i.e. retrofit devices, which may be added to a PC. Such retrofit devices are typically blowers which are adapted for disposal within the space reserved for additional disk drives.